apt-cdrom is a simple command to add CDROMs to apt's sources.list file. Its syntax is a variation on this basic command line:
apt-cdrom uses information from your /etc/fstab if you don't specify where's the CDROM drive.
apt-config is a tool to read apt's apt.conf file and is very useful to dump it to screen. Its syntax is a variation of these basic options:
Show the configuration options in the screen